Developers today are building the home stock that will still exist in 2050, the date the UK government has set for reducing greenhouse gas emissions to net zero.
Change in house design to make energy-efficient, low-carbon homes the norm must happen now if we are to meet that deadline.
Consequently, developers are rethinking their approach to heating, ventilation and insulation to make low-emission housing a reality, but what do they need to know to make the transition smooth and effective?
Government policy is driving a market rethink
Headline legislation in this area is the Future Homes Standard - renamed the Future Homes and Buildings Standard in December 2021. The central point of the standard is a drive to ensure that all homes built from 2025 will produce 75-80% less carbon emissions than homes delivered under current regulations.
The standard recognises that it’s significantly cheaper and easier to install energy efficiency and low carbon heating measures when homes are built, rather than retrofitting them. According to the standard, no new house should be reliant on fossil fuels or need refurbishment to reach zero-carbon as the electricity grid continues to decarbonise. The standard also introduces a ‘fabric-first approach’ that involves maximising the performance of the materials that make up the building itself, consequently improving insulation and airtightness.
The steps to energy-efficient houses
The pathway to low-emission homes via the Future Homes and Buildings Standard is a stepped one, making changes to Building Regulations Part L (conservation of fuel and power) and Part F (ventilation).
Stage one encourages homes that are future-proofed for the longer term and stipulates that new homes will be expected to produce 31% less greenhouse gas emissions compared to pre-2021 standards. In stage two, the government will consult about technical aspects of the Future Homes and Buildings Standard in 2023 before introducing legislation in 2024 ahead of implementing updated regulations to come into force in 2025.
The key date for developers is 15 June 2023, because from then the new regulations will apply to all buildings where work has not started regardless of the date that building consent was obtained.
Success depends upon a new approach to heating
The Future Homes and Buildings Standard relies upon building new homes with high energy efficiency to reduce the burden on the National Grid and help it to decarbonise faster.
Combine this with the clear message from the International Energy Agency that no new gas boilers should be sold after 2025 if net zero targets are to be met by 2050, and the focus for developers has to be on fitting low-carbon heating system elements such as heat pumps, together with the appropriately sized radiators or underfloor heating, increased insulation and heat exchange systems.
Heat pumps are the future
Heat pumps are likely to be the main successor to gas boilers because they reduce a home’s carbon footprint by using cleaner electricity and are currently the most cost-effective form of heating using electricity. They offer an average Coefficient of Performance (COP) of 2.5 or more, meaning they produce 2.5 kilowatts of heating or cooling power for every kilowatt of electricity. Ground-source heat pumps tend to have an efficiency of between 2.5 and 3, while air-source heat pumps have an average efficiency of between 1.5 and 3. This is in comparison to an electric fire or gas boiler that has an average COP of one.
High-grade insulation is critical
Effective insulation should always be a priority for new build houses before any renewable technology, particularly heat pumps, is considered. Developers shouldn’t look to renewable technology to compensate for poor insulation.
Good insulation is particularly important where a heat pump is going to be used, because the lower the flow temperature from the heat pump, the higher its efficiency, and the less energy it draws from the National Grid. In a poorly insulated building, a higher flow temperature is required, meaning the heat pump will cost more to run and have higher carbon emissions. There’s also a high likelihood that, without adequate insulation, the heat pump may not be able to provide sufficient heat to stop the home’s occupants from feeling cold. Developers should consider a range of insulation strategies, including cavity wall insulation, loft insulation, high-specification double glazing and underfloor insulation.
Underfloor heating is the best partner for heat pumps
Maximising the efficiency of a heat pump extends beyond the pump itself to include the system that circulates heat from the pump around the house. The compressor in a heat pump works most efficiently (and uses the lowest levels of electricity) when there’s only a small temperature difference between the outside source temperature and the water temperature needed in the heat circulating system (radiators or underfloor heating).
The critical factor here is the size of the heat-emitting surface. Radiators with a larger surface area can deliver more heat into the room without increasing the water temperature. Therefore, attaching a heat pump to conventional radiators can be a false economy because they have a smaller surface area, meaning the heat pump must run at a higher temperature.
Underfloor heating is much more effective when combined with a heat pump because it offers the greatest heat emitting surface, so can run at very low temperatures. For example, it can be run as low as 30 degrees to achieve a room temperature of 20 degrees - as opposed to a radiator running at 60 degrees to achieve a 20-degree room temperature. Plus, underfloor heating is more aesthetically pleasing to home buyers, avoiding large, visible radiators.
Heat recovery cuts heat pump energy requirements
Heat recovery systems are also an effective part of the low-carbon house, taking some of the heating strain off the heat pump and enabling it to run at a lower temperature. On average, a heat recovery system can retain and reuse up to 90% of the heat that’s usually wasted, reducing the home’s heating requirements. It also addresses the need for ventilation and clean indoor air in a house that’s relatively airtight for insulation and energy efficiency reasons. Research reveals that new build houses can achieve up to 30% savings on heating bills by incorporating a heat recovery system. Find out more about MVHR (Mechanical Ventilation Heat Recovery)
Start building the future today
Making the Future Homes and Buildings Standard a reality needs to start with a holistic approach to heating (and cooling) new build homes. A combination of a heat pump linked to underfloor heating, high-quality insulation and a heat recovery system is the most effective combination for success.
Indoor Climate Solutions at Wavin
At Wavin, our purpose is to build healthy sustainable environments. Our tailored indoor climate solutions feature our market-leading systems and products including underfloor heating, heat interface units, MVHR and single controls (interfacing with all of these technologies). They provide the following benefits:
